FactoryBean that creates a JPA
EntityManagerFactory according to JPA's standard
standalone bootstrap contract. This is the simplest way to set up a
shared JPA EntityManagerFactory in a Spring application context; the
EntityManagerFactory can then be passed to JPA-based DAOs via
dependency injection. Note that switching to a JNDI lookup or to a
LocalContainerEntityManagerFactoryBean
definition is just a matter of configuration!

Configuration settings are usually read from a META-INF/persistence.xml
config file, residing in the class path, according to the JPA standalone bootstrap
contract. Additionally, most JPA providers will require a special VM agent
(specified on JVM startup) that allows them to instrument application classes.
See the Java Persistence API specification and your provider documentation
for setup details.

This EntityManagerFactory bootstrap is appropriate for standalone applications
which solely use JPA for data access. If you want to set up your persistence
provider for an external DataSource and/or for global transactions which span
multiple resources, you will need to either deploy it into a full Java EE 5
application server and access the deployed EntityManagerFactory via JNDI,
or use Spring's LocalContainerEntityManagerFactoryBean with appropriate
configuration for local setup according to JPA's container contract.

Note: This FactoryBean has limited configuration power in terms of
what configuration it is able to pass to the JPA provider. If you need more
flexible configuration, for example passing a Spring-managed JDBC DataSource
to the JPA provider, consider using Spring's more powerful
LocalContainerEntityManagerFactoryBean instead.